EP4273202A1 - Procédé de fabrication de bandes minces adhésives sensibles à la pression - Google Patents

Procédé de fabrication de bandes minces adhésives sensibles à la pression Download PDF

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Publication number
EP4273202A1
EP4273202A1 EP23171943.6A EP23171943A EP4273202A1 EP 4273202 A1 EP4273202 A1 EP 4273202A1 EP 23171943 A EP23171943 A EP 23171943A EP 4273202 A1 EP4273202 A1 EP 4273202A1
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EP
European Patent Office
Prior art keywords
carrier layer
pressure
layer
adhesive
sensitive adhesive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23171943.6A
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German (de)
English (en)
Inventor
Norbert Grittner
Karsten Kuss
Anika PETERSEN
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Tesa SE
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Tesa SE
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Publication date
Application filed by Tesa SE filed Critical Tesa SE
Publication of EP4273202A1 publication Critical patent/EP4273202A1/fr
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/10—Adhesives in the form of films or foils without carriers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature

Definitions

  • the invention relates to a method for producing a pressure-sensitive adhesive tape, which is particularly suitable for producing thin pressure-sensitive adhesive tapes.
  • a corresponding pressure-sensitive adhesive tape and a device for carrying out the method are also disclosed.
  • Joining separate elements is one of the central processes in manufacturing technology.
  • bonding i.e. joining using an adhesive
  • pressure-sensitive adhesive tapes are particularly relevant in which a pressure-sensitive adhesive ensures the adhesive effect, which is permanently sticky and adhesive under normal environmental conditions.
  • Corresponding pressure-sensitive adhesive tapes can be applied to a substrate by pressure and remain stuck there, but can later be removed more or less without leaving any residue.
  • the primary object of the present invention was to eliminate or at least reduce the disadvantages of the prior art described above.
  • the object of the present invention to provide a method for producing a pressure-sensitive adhesive tape with which advantageous pressure-sensitive adhesive tapes with particularly thin adhesive layers can be obtained. It was an object of the present invention that the pressure-sensitive adhesive tapes produced using the method to be specified should be able to be produced with adhesive layers that are as uniformly shaped as possible, in particular with a uniform cross-sectional profile. It was a desirable requirement of the present invention that the adhesive properties of the PSA used for production should not be adversely affected by the method to be specified, or at least only to a small extent, and that overall high-performance PSA tapes can be obtained.
  • the method to be specified should have an advantageous convertibility, which enables a quick product change and an uncomplicated changeover to a different layer thickness of the adhesive layer when producing pressure-sensitive adhesive tapes.
  • the process to be specified should be able to be operated continuously and ideally with a high turnover, and the process to be specified should desirably have a high level of process and work safety.
  • the method to be specified should be able to be implemented with as few equipment modifications as possible by using device components that are regularly used in the area of adhesive bonding technology become.
  • the process to be specified should be usable for essentially all types of pressure-sensitive adhesives.
  • a web-shaped starting adhesive layer which comprises a chemically at least partially uncrosslinked pressure-sensitive adhesive and which is guided in a guide arrangement at the speed v 1 is transferred to a second guide arrangement, and is guided in this at a higher speed v 2 , so that the PSA is stretched during transfer and reduced in thickness, the PSA being reduced as a result of the stretching or that produced in this way
  • Anisotropy of the pressure-sensitive tack in combination with the tension generated during stretching promotes peeling and transfer, provided that the adhesive mass stretched in this way is then at least partially relaxed in order to restore the pressure-sensitive tack or its anisotropy, as defined in the claims.
  • the pressure-sensitive adhesive is transferred, for example, from a first liner to a second liner, which is guided over a roller running with advance, so that a stretching occurs in the web direction, which synergistically reduces the pressure-sensitive adhesive of the stretched pressure-sensitive adhesive, so that a light Detachment of the adhesive from the first liner is promoted, so that particularly reliable removal can be ensured, particularly if these liners are provided with a release coating.
  • This can occur particularly at high stretch rates
  • Reduction of the pressure-sensitive tack can advantageously be so pronounced that efficient removal is possible for pressure-sensitive adhesives with a very high adhesive strength and/or for non-release-coated liners.
  • the pressure-sensitive tack which otherwise often stands in the way of the implementation of many plastics processing methods known from the prior art for pressure-sensitive adhesives, is advantageously temporarily at least partially reduced and then only restored in the course of relaxation.
  • the thickness of the adhesive layer is advantageously reduced approximately in proportion to the ratio of the web speeds v 1 and v 2 , ie the web speeds before and after the drafting system.
  • This method which can be connected, for example, immediately after the adhesive layer has been formed, for example immediately behind a smoothing unit used for forming, makes it possible to produce adhesive layers with very small layer thicknesses, for example significantly less than 200 ⁇ m, with high precision.
  • This makes it possible in a synergistic manner to run the process upstream of the drafting system essentially without regard to the final desired thickness of the end product and rather to design it for maximum stability and efficiency by only setting thicknesses of the adhesive layer up to the drafting system are particularly easy to handle in terms of process engineering. This greatly reduces the requirements for the equipment used.
  • this method can be used to produce different pressure-sensitive adhesive tapes with different thicknesses of the adhesive layer without having to change the settings during the production of the initial composite, for example with regard to the rollers of the calender, with the thickness being able to be adjusted advantageously by controlling the speeds. so that the layer thickness can also be changed during ongoing operation.
  • This eliminates the need for shutdown and start-up processes, which are not very efficient in terms of time and costs, or complex parameter changes to the smoothing unit, which in turn can be aligned to optimal layer thickness precision in the initial composite
  • the high layer thickness precision obtained in this way is advantageously transferred to the pressure-sensitive adhesive tape produced with a thin layer.
  • the invention also relates to the corresponding pressure-sensitive adhesive tape, which can be produced using the method according to the invention.
  • the pressure-sensitive adhesive tape according to the invention can be obtained at any time after process step d), whereby further process steps can also be carried out beforehand, as described below.
  • the pressure-sensitive adhesive tape can in particular be obtained as a carrierless pressure-sensitive adhesive tape by designing the second carrier layer as a liner, i.e. as a separating layer, as disclosed below, which is particularly preferred in practice.
  • the method can be carried out in such a way that the second carrier layer is selected so that it can form the carrier in the later pressure-sensitive adhesive tape, which, in contrast to the separating layer designed for easy detachment, is firmly connected to the pressure-sensitive adhesive layer.
  • the invention accordingly also relates to a pressure-sensitive adhesive tape, produced or producible using the method according to the invention, comprising at least one pressure-sensitive adhesive layer derived from the adhesive layer and optionally a carrier layer or a separating layer, wherein the carrier layer or the separating layer is preferably derived from the second carrier layer.
  • the pressure-sensitive adhesive tape comprises the second carrier layer as a carrier layer of the pressure-sensitive adhesive tape.
  • an example is a method according to the invention, wherein the pressure-sensitive adhesive tape does not comprise a carrier layer, the adhesive layer being arranged on a separating layer.
  • An example is a method according to the invention, in which the pressure-sensitive adhesive tape is rolled up after production.
  • the pressure-sensitive adhesive tape comprises a pressure-sensitive adhesive layer and optionally a carrier layer or a release layer.
  • the adhesive layer of the method according to the invention corresponds to the pressure-sensitive adhesive layer after the pressure-sensitive adhesive tape has been removed, whereas a carrier layer removed together with the adhesive layer becomes the carrier layer or separating layer. The features of the adhesive layer disclosed for the method according to the invention can therefore be transferred accordingly to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tapes according to the invention.
  • a web-shaped release material a so-called release liner
  • the release material preferably being selected from the group consisting of polyethylene, polypropylene, Polyethylene terephthalate, paper and combinations of these materials, the release material being particularly preferably coated on one or both sides with a release layer, preferably a silicone release layer, the silicone release layer being very particularly preferably producible by crosslinking a crosslinkable silicone system comprising one or more polysiloxanes.
  • a web-shaped initial composite is first produced or provided.
  • This initial composite is web-shaped, as is regularly the case in the field of adhesive technology for adhesive tapes or adhesive strips, and following the method according to the invention, for example, separation into adhesive labels or similar products can also take place.
  • the term web-shaped means that it is a flat structure whose extent in the xy plane is significantly larger than the extent in the z direction orthogonal to the xy plane, whereby the extent within the xy plane in one direction is significantly larger than the extent transverse to this longitudinal direction. In practice it is for the expert It is easy to determine whether an initial composite is web-shaped, as this is a typical shape in the area of adhesive tapes.
  • the initial composite comprises at least two components, which in turn are web-shaped.
  • This is the first carrier layer and a starting adhesive layer, which comprises a pressure-sensitive adhesive and is therefore itself at least partially pressure-sensitively adhesive.
  • the method according to the invention can advantageously be used “off-line” by simply providing the corresponding initial composite, which is obtained, for example, from a supplier or a separate production facility.
  • An example is a method according to the invention, in which the web-shaped starting composite is provided in method step a), preferably from a roll of material.
  • the web-shaped starting composite is produced in method step a) by coating the first carrier layer with the chemically at least partially uncrosslinked PSA, the coating preferably comprising drying and/or cooling of the chemically at least partially uncrosslinked PSA, and /or wherein the web-shaped starting composite is produced in process step a), the starting adhesive layer being formed in a calender.
  • the starting adhesive layer comprises a pressure-sensitive adhesive and in practice will in many cases even consist essentially entirely of the pressure-sensitive adhesive.
  • a pressure-sensitive adhesive is an adhesive that has pressure-sensitive adhesive properties, ie the property of forming a permanent bond to an adhesive base even under relatively weak pressure.
  • Pressure-sensitive adhesive tapes can usually be removed from the adhesive base after use essentially without leaving any residue and are usually permanently self-adhesive even at room temperature, which means that they have a certain viscosity and stickiness to the touch, so that they wet the surface of a substrate even with slight pressure.
  • a pressure-sensitive adhesive can be viewed as an extremely high-viscosity liquid with an elastic component, which therefore has characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive ability described above. It is assumed that with corresponding PSAs mechanical deformation leads to both viscous flow processes and the build-up of elastic restoring forces. The proportionate viscous flow serves to achieve adhesion, while the proportionate elastic restoring forces are necessary in particular to achieve cohesion.
  • the connections between rheology and pressure sensitive tack are known in the prior art and, for example, in " Satas, Handbook of Pressure Sensitive Adhesives Technology", Third Edition, (1999), pages 153 to 203 , described.
  • an adhesive is preferably understood to be pressure-sensitive and therefore a pressure-sensitive adhesive if, at a temperature of 23 ° C in the deformation frequency range of 10 0 to 10 1 rad/sec, G' and G" are each at least partially in the range of 10 3 to 10 7 Pa.
  • the pressure-sensitive adhesive comprises one or more (co-)polymers, the (co-)polymers being selected from the group consisting of poly(meth)acrylates, polyurethanes and rubbers, in particular polyisoprene rubbers, styrene -Butatiene rubbers, ethylene-propylene-diene rubbers, polysiloxanes, polyepoxides and isoprene rubbers.
  • the pressure-sensitive adhesive comprises one or more additives which are selected from the group consisting of adhesive resins and fillers.
  • the PSA comprises solvent in a mass proportion of 10% or less, preferably 1% or less, particularly preferably 0.1% or less, based on the mass of the PSA.
  • a method according to the invention is preferred, wherein the PSA is a foamed PSA, preferably a syntactically foamed PSA.
  • the PSA used is not completely chemically cross-linked, since a corresponding complete chemical cross-linking would stand in the way of efficient subsequent relaxation after stretching.
  • a chemically at least partially uncrosslinked PSA has a macroscopic relaxation ability, ie the ability to relax after mechanical stretching, so that anisotropies generated during stretching in the adhesive layer can be broken down over time through relaxation.
  • chemical crosslinking differs from any physical crosslinking that may occur, the influence of which can be easily handled by a person skilled in the art through the choice of process parameters, in particular the processing temperature, so that any physical crosslinking that may be present does not stand in the way of stretching and relaxation.
  • chemical crosslinking refers to the usual step in the field of adhesive technology of crosslinking individual (co-)polymers of a pressure-sensitive adhesive, for example via functional groups or radiation-induced reactive sites which are present in the respective (co-)polymers or are generated and are intended to react with one another, if necessary using a chemical crosslinker and/or using suitable initiation conditions, and thereby increase the degree of linkage in the (co)polymer, thereby improving the physicochemical properties, for example the solubility of the crosslinked (Co-)polymers or the cohesion of the PSA, and branched (co-)polymers with increased molecular weights or continuous polymer networks are obtained.
  • a PSA is considered to be chemically at least partially uncrosslinked if the PSA has the ability to relax under the relaxation conditions selected in process step d).
  • the PSA has the ability, under the relaxation conditions selected in process step d), to compensate for a macroscopic anisotropy of the physico-chemical properties, in particular the PSA, in the material over time by relaxation caused by stretching, so that the corresponding macroscopic properties, in particular the adhesive strength or the shrinkage, between the x-direction and the y-direction by 20% or less, preferably by 10% or less, particularly preferably by 5% or less, very particularly preferably 1% or less, differentiate.
  • the relaxation conditions selected in process step d) are defined in particular by the relaxation temperature and the time available for the relaxation.
  • the chemically at least partially uncrosslinked PSA can therefore be relaxed under the relaxation conditions selected in process step d), so that anisotropy in the material generated by the stretching can be reduced over time and a pressure-sensitive tack reduced by the stretching can be restored.
  • a PSA is in any case considered to be a chemically at least partially uncrosslinked PSA if the relaxation ability of the PSA under the relaxation conditions selected in process step d) is 50% or more, preferably 70% or more, particularly preferably 90% or more , very particularly preferably 99% or more, of the relaxation ability of the completely uncrosslinked PSA, whereby in case of doubt the relaxation ability is also related to the ability to restore the adhesive strength, for example determined according to DIN EN ISO 29862-2019, or the isotropy of the shrinkage, preferably the isotropy of the shrinkage is evaluated.
  • the initial composite is introduced into the stretching arrangement, also known as the drafting system, whereby the web-shaped initial composite is guided at a first speed v 1 , which is implemented via a first guide arrangement.
  • This first guide arrangement can, for example, contain a large number of rollers, rollers or similar elements which serve to move the web-shaped output composite in the web direction.
  • the web-shaped initial composite can be guided over a driven roller, which contacts the initial composite on the side of the first carrier layer.
  • the PSA is then removed from the first carrier layer.
  • This works particularly well if the initial composite is guided over a curvature in the area in which the peeling takes place, which enables tangential detachment, as can be achieved, for example, by the roller mentioned above, but also by a so-called detachment edge, which is sometimes also referred to by experts as a delaminating sword.
  • method step c) can be implemented particularly well and particularly precisely, in particular not affecting the bond strength between the adhesive layer and the first Carrier layer is dissolved prematurely, that is, the removal cannot continue through the initial adhesive bond against the direction of the web.
  • the use of guide rollers is particularly advantageous, with particularly controlled process management being achieved if a guide roller is arranged on both sides of the initial assembly, through which the initial assembly is passed, so that it receives stabilization, whereby it is in In this case, it is advisable to provide a further carrier layer, as will be disclosed below.
  • the guide arrangement comprises one or more, preferably two or more, particularly preferably exactly two, guide rollers or a release edge, and/or wherein the initial composite is guided over a guide roller or a release edge at the time the pressure-sensitive adhesive is removed is, whereby the initial composite is preferably passed between two guide rollers.
  • the speed v 1 can advantageously be caused by the rotation of the guide rollers.
  • a method according to the invention is therefore preferred, in which the superficial tangential speed of the guide rollers corresponds to the speed v 1 , and/or in which the speed v 1 of the initial assembly is caused by the rotation of the guide rollers.
  • Typical rollers can be used as guide rollers, as are also known from other areas of processing PSAs.
  • An example is a method according to the invention, in which at least one of the guide rollers, preferably all of the guide rollers, has a diameter in the range of 25 to 200 mm, preferably in the range of 50 to 100 mm, and/or in which at least one of the guide rollers, preferably all of the guide rollers, has a diameter in the range of 0.025*b to 0.2*b, preferably in the range of 0.05*b to 0.1*b, where b is the web width of the guide rollers, where b is particularly preferably in the range of 0, 5 to 2.5 m, most preferably in the range from 1.0 to 2.0 m.
  • Rotary element of the second guide arrangement can also be used with larger diameters of, for example, up to 500 mm.
  • larger diameters for example, up to 500 mm.
  • the web-shaped starting composite comprises a web-shaped third carrier layer arranged on the side of the starting adhesive layer facing away from the first carrier layer.
  • a method according to the invention is also preferred, wherein the starting adhesive layer is guided in process step b) between the first carrier layer and the third carrier layer, preferably between two guide rollers, and wherein the third carrier layer is removed from the starting adhesive layer before the pressure-sensitive adhesive is transferred.
  • the first carrier layer as well as any third carrier layer that may be present, can be formed by typical process liners that are regularly used in the field of adhesive technology and that are comprehensively known to those skilled in the art from the prior art. Preference is given to a method according to the invention, wherein the first carrier layer and/or the third carrier layer, preferably the first carrier layer and the third carrier layer, comprises one or more materials selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, paper and combinations of these materials, with the first carrier layer preferably made of these materials.
  • a method according to the invention is preferred, wherein the first carrier layer and/or the third carrier layer, preferably the first carrier layer and the third carrier layer, have an average thickness in the range from 20 to 150 ⁇ m, preferably in the range from 30 to 125 ⁇ m, particularly preferably in the range from 40 to 100 ⁇ m.
  • this enables an embodiment of the first guide arrangement in which, instead of a conventional process liner, the carrier layers can be formed by a circumferential webbing or a comparable reusable arrangement, which together with the adhesive layer form the initial composite and from which the pressure-sensitive adhesive in process step c) is deducted.
  • the carrier layers can be formed by a circumferential webbing or a comparable reusable arrangement, which together with the adhesive layer form the initial composite and from which the pressure-sensitive adhesive in process step c) is deducted.
  • the first guide arrangement comprises one or more, preferably two or more, guide rollers, wherein the first carrier layer and / or the third carrier layer, preferably the first carrier layer and the third carrier layer, through a webbing running around the guide rollers are formed, the webbing preferably being made of steel and/or plastic.
  • the carrier layers are provided with a so-called release layer, which facilitates the step of removing the PSA by increasing the adhesion of the PSA Adhesive layer on the release-coated carrier layer is reduced.
  • This is particularly advantageous for processes in which only a relatively small stretching is to be achieved, which leads to a comparatively small reduction in the pressure-sensitive adhesive, so that in many cases it is expedient to promote easy removal of the pressure-sensitive adhesive through such additional measures.
  • a corresponding design is particularly important, especially in the design with circumferential belt straps, in order to ensure good long-term release of the PSA in this case too.
  • first carrier layer and/or the third carrier layer preferably the first carrier layer and the third carrier layer
  • a release layer preferably with a silicone release layer
  • silicone Release layer can preferably be produced by crosslinking a crosslinkable silicone system comprising one or more polysiloxanes.
  • the PSA is removed from the first carrier layer, so that the initial composite is dissolved.
  • the peeled-off pressure-sensitive adhesive is transferred to a web-shaped second carrier layer, so that a second composite is obtained, which is referred to as an adhesive composite in the context of the present invention.
  • the second carrier layer and thus also the web-shaped adhesive composite after the removal of the peeled-off PSA is guided at a second speed v 2 , which in turn is realized by a second guide arrangement.
  • This second guide arrangement includes, in addition to potential further components that can in principle be comparable to those of the first guide arrangement, for example rollers and suspensions, preferably a rotation element over which the second carrier layer is guided and which in this case represents the actual stretching unit. Even if deviations from ideal cylindrical symmetry are conceivable, at least in principle, it has also proven to be preferable for the rotation element to be designed as a roller. A method according to the invention is therefore preferred, wherein the second Guide arrangement comprises a, preferably driven, rotating element, preferably a roller, over which the second carrier layer is guided.
  • this rotating element not only serves to guide the second carrier layer, but also determines the speed v 2 of the adhesive bond, because it is designed, for example, as a driven rotating element.
  • a method according to the invention is preferred, wherein the superficial tangential speed of the rotating element corresponds to the speed v 2 , and/or wherein the speed v 2 of the adhesive composite is caused by the rotation of the rotating element.
  • typical roller diameters come into consideration for the rotating element, and in the inventors' opinion it is particularly advantageous to match the diameter of the rotating element to the diameter of the guide rollers in the first guide arrangement.
  • An example is a method according to the invention, wherein the rotating element has a diameter in the range of 50 to 200 mm, preferably in the range of 100 to 150 mm.
  • a method according to the invention is preferred, wherein the rotating element has a diameter in the range from 0.1*df to 0.5*df, preferably in the range from 0.15*df to 0.3*df, where df is the diameter of the guide roller the first leadership arrangement.
  • the speed v 2 is greater than the speed v 1 .
  • the second carrier layer and thus the adhesive composite move faster in the web direction than the first carrier layer and the initial composite.
  • the peeled-off PSA is stretched during transfer and its thickness is reduced by the advance of the second guide arrangement as a result of the stretching.
  • the extent of the thickness reduction advantageously correlates with the set speed ratio, so that the reduction in thickness approximately corresponds to the reciprocal of the speed ratio D 2 /D 1 ⁇ V 1 /V 2 .
  • small changes in thickness can also be made using the method according to the invention realize if, for example, the speed ratio is only slightly above 1.
  • the speed ratio v 2 /v 1 is greater than 1.1, preferably greater than 2, particularly preferably greater than 5, very particularly preferably greater than 7, particularly preferably greater than 10. Additionally or alternatively, preference is given to a method according to the invention, wherein the speed ratio v 2 /v 1 is less than 35, preferably less than 30, particularly preferably less than 25, very particularly preferably less than 20, particularly preferably less than 15.
  • a method according to the invention is also preferred, in addition or as an alternative, in which the average thickness of the adhesive layer is 10% or more, preferably 30% or more, particularly preferably 50% or more, very particularly, compared to the average thickness of the starting adhesive layer is preferably reduced by 70% or more, particularly preferably by 90% or more.
  • the inventors have succeeded in specifying suitable ranges for the speeds v 1 and v 2 with which particularly reliably good adhesive layers can be obtained in the adhesive bond.
  • a process according to the invention is preferred, with the speed v 1 being in the range from 5 to 300 m/min, preferably in the range from 10 to 150 m/min, particularly preferred in the range from 20 to 100 m/min, and wherein the speed v 2 is in the range from 10 to 350 m/min, preferably in the range from 20 to 200 m/min, particularly preferably in the range from 30 to 150 m/min , lies.
  • the average thickness of the adhesive layer in the adhesive bond being in the range from 10 ⁇ m to 2 mm, preferably in the range from 20 ⁇ m to 1 mm, particularly preferably in the range from 30 ⁇ m to 0.5 mm, and /or wherein the average thickness of the adhesive layer in the adhesive bond is 500 ⁇ m or less, preferably 200 ⁇ m or less, particularly preferably 100 ⁇ m or less.
  • a particularly gentle procedure results when the method according to the invention is carried out several times in succession, so that a stretched and then relaxed adhesive composite is again entered into a method according to the invention as the starting material, in that this in turn functions as the starting adhesive composite and is further stretched in order to to further reduce the average thickness.
  • This procedure is particularly advantageous because the individual extent of stretching is kept to a manageable extent by comparatively low speed ratios, so that strong mechanical stress on the PSA is avoided and the risk of cohesive failure during peeling or tearing during stretching is reduced, while at the same time adhesive layers are also present a small thickness can be obtained.
  • a method according to the invention is therefore preferred, wherein the web-shaped starting composite is produced using a method according to the invention, so that the average thickness of a pressure-sensitive adhesive tape produced using a method according to the invention is further reduced using the method according to the invention.
  • the advantageous control of the thickness reduction via the speed ratio of the guide in the first or second guide arrangement makes it particularly easy to increase the thickness of the adhesive layer obtained in the process, if necessary even during the process Adapt the manufacturing process quickly and easily.
  • This makes it particularly easy to obtain adhesive tapes with completely different thicknesses of the adhesive layers from the essentially same initial adhesive composite by simply adjusting the stretching parameters.
  • it is particularly preferred to use the method according to the invention essentially without any modifications to the apparatus in the production of adhesive tapes with different average thicknesses of the adhesive layer and, accordingly, to benefit particularly clearly from the advantages of the method according to the invention.
  • a method according to the invention is preferred, the method being used one after the other for the production of two or more different pressure-sensitive adhesive tapes with the same type of pressure-sensitive adhesive, the average thickness of the pressure-sensitive adhesive layer differing by 10% or more, preferably 25% or more, the average thickness of the starting adhesive layer is changed by 5% or less, thereby changing the speed ratio v 2 /v 1 .
  • the second carrier layer can in principle be designed according to the same requirements as those disclosed above for the first carrier layer or third carrier layer.
  • a design as a webbing and a coating with a release layer are also conceivable.
  • the second carrier layer will in many cases form the carrier of the pressure-sensitive adhesive tape to be produced or a liner for receiving a carrierless pressure-sensitive adhesive tape, the design as a webbing for the second carrier layer is less preferred, since these are more suitable for specific applications .
  • the second carrier layer comprises one or more materials selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, paper and combinations of these materials, wherein the second carrier layer preferably consists of these materials. Additionally or alternatively, a method according to the invention is preferred, wherein the second carrier layer has an average thickness in the range from 20 to 150 ⁇ m, preferably in the range from 30 to 125 ⁇ m, particularly preferably in the range from 40 to 100 ⁇ m.
  • the second carrier layer is formed by a webbing running around the guide rollers, the webbing preferably being made of steel and/or plastic or fiber-reinforced plastic.
  • a method according to the invention is preferred both for the design as a liner and as a webbing, wherein the second carrier layer is coated on the side facing the pressure-sensitive adhesive with a release layer, preferably a silicone release layer, the silicone release layer being particularly preferably produced by crosslinking a crosslinkable silicone system comprising one or more polysiloxanes.
  • the second carrier layer comprises one or more materials which are selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyesters, in particular polyethylene terephthalate, polylactides, Polyamides, cycloolefin copolymers, paper, fabric and nonwoven fabric, the second carrier layer in this case preferably not comprising a release layer on the side facing the pressure-sensitive adhesive layer.
  • the PSA is transferred as described above, with a new adhesive bond being created compared to the initial adhesive bond.
  • the adhesive layer in addition to a first PSA, also includes a second PSA arranged above it, possibly even as its own adhesive layer, and that the second PSA in the adhesive composite produced mediates the contact between the first PSA and the second carrier layer.
  • the above definition does not mean that only the PSA is transferred in process step c).
  • PSA is removed from the first carrier layer
  • it can also be used to remove further parts of the starting adhesive layer, in particular further layers of other PSAs as well as any additional layers which can be arranged inside the PSA or on the side facing away from the first carrier layer, even if these have the PSA in the adhesive layer separate two parts.
  • a pressure-sensitive adhesive it is possible for a pressure-sensitive adhesive to be divided into two partial compositions by an inner layer, one of which is drawn off from the first carrier layer as a pressure-sensitive adhesive, while the other partial composition establishes contact with the second carrier layer.
  • the pressure-sensitive adhesive is stretched during transfer, it makes sense in this case, which in practice will probably be more relevant for very specific applications, to also form any existing inner layers from a stretchable material, with the expert checking the stretchability of the inner layer in the Practice is functionally adapted to the stretching of the PSA intended in the method according to the invention, so that the inner layer does not hinder this stretching or does not significantly hinder it.
  • a method according to the invention is therefore preferred for certain applications, wherein the starting adhesive layer comprises one or more web-shaped inner layers which are at least partially embedded in the pressure-sensitive adhesive, the inner layers being removed and transferred together with the pressure-sensitive adhesive, the inner layers being made of a stretchable material.
  • the tackiness of pressure-sensitive adhesives during processing sometimes represents a problem that can make it difficult to easily adapt other plastics processing methods.
  • the inventors initially assumed that a reduction in thickness by stretching would fail because the PSA would adhere too strongly to the carrier layers, even with excellently selected release coatings, in order to enable reproducible product quality and material defects when peeled off reliably prevented.
  • stretching the PSA reduces its tackiness or induces an anisotropy of the PSA and thereby promoting the peeling in a reliable manner, so that the peeling together with the tension generated in the PSA during stretching promotes or causes the peeling of the PSA.
  • the subsequent relaxation of the stretched pressure-sensitive adhesive then serves to reduce tensions in the adhesive layer and to recover the desired pressure-sensitive tack or to restore isotropy, so that an effect can be used, as is known, for example, from adhesive strips for fastening wall elements for example, are available on the market under the name “Tesa Powerstrips”.
  • this is a method according to the invention, wherein the removal of the PSA is promoted or effected by stretching the PSA in the mold, preferably promoted, so that the adhesion of the PSA to the first carrier layer is reduced by the stretching.
  • a method according to the invention wherein the initial composite is guided over a guide roller or a release edge at the time of peeling off the PSA and wherein the first carrier layer and the second carrier layer are guided relative to one another in such a way that the PSA is pulled off essentially tangentially, whereby the pressure-sensitive adhesive is preferably also placed tangentially on the second carrier layer.
  • a method according to the invention is preferred, wherein the first carrier layer and the second carrier layer are guided relative to one another in such a way that the initial adhesive layer is pulled off essentially tangentially from the first carrier layer during transfer.
  • the inventors suggest that the stretching length, ie the length between the first guide arrangement or the first carrier layer and the second guide arrangement or the second carrier layer, ie without contact to a carrier layer, stretched PSA, is selected as short as possible, at least as short as the apparatus structure allows, in order to avoid the risk of a reduction in the web width during stretching (so-called "neck-in”) and the desired longitudinal stretching in the web direction to transport.
  • a method according to the invention is preferred, wherein in method step c) the stretching length of the peeled off and transferred PSA between the first guide arrangement and the second guide arrangement, measured along the PSA stretched between the guide arrangements, is in the range from 0.5*r to 10*r, preferably in the range from 0.7*r to 5*r, particularly preferably in the range from 0.9*r to 2.5*r, where r is the radius of the rotation element of the second guide arrangement.
  • the PSA is relaxed after stretching in order to dissolve the orientation of the (co)polymer strands in the material caused by the stretching and thereby improve the pressure-sensitive tack of the PSA or, in general, the isotropy of the macroscopic properties of the PSA as much as possible largely restored.
  • relaxation under ambient conditions, i.e. at room temperature, is often sufficient.
  • the inventors suggest controlling the temperature of the PSA during relaxation, for example with a heating element, this step being particularly recommended if a PSA is used which is based on synthetic rubbers as a (co-)polymer, since these In many cases, at room temperature, the relaxation behavior is insufficient, ie too slow, to achieve sufficient relaxation within the usual processing times.
  • the stretched pressure-sensitive adhesives not only pass through a zone with an elevated temperature, but also, as part of a multi-stage relaxation process, several temperature zones arranged one behind the other with different temperatures, for example in the form of heating elements arranged one behind the other.
  • a method according to the invention is therefore preferred, wherein the relaxation of the stretched PSA in process step d) includes tempering the PSA in the adhesive layer, preferably by means of a heating element, in particular a radiant heater or a heating roller, and / or wherein the relaxation of the stretched PSA in process step d) by locally heating the stretched PSA is conveyed or effected in the adhesive layer.
  • a heating element in particular a radiant heater or a heating roller
  • the relaxation of the stretched PSA in process step d) by locally heating the stretched PSA is conveyed or effected in the adhesive layer.
  • the relaxation of the stretched pressure-sensitive adhesive in process step d) takes place in a multi-stage relaxation process, the multi-stage relaxation process preferably involving relaxation at two or more, preferably three or more, different temperatures, preferably temperatures of 30 ° C or more , includes.
  • the person skilled in the art expediently sets the degree of crosslinking that is desired for the respective application of the pressure-sensitive adhesive tape.
  • the (co-)polymers of the PSA are thus cross-linked with one another to the extent that the physico-chemical properties correspond to the requirements necessary for the application in the desired manner, in particular through specific cohesion, shear strength or thermal shear strength.
  • the stretching of the PSA results in a reduction in the PSA properties, whereby a high degree of chemical crosslinking of the stretched PSA can potentially prevent efficient relaxation of the system and, so to speak, fixes it in the stretched state. It is therefore expedient to largely relax the PSA before or during crosslinking. Accordingly, a method according to the invention is preferred, wherein the chemical crosslinking in method step e) takes place in such a way that the macroscopic properties of the chemically crosslinked adhesive layer essentially correspond to the macroscopic properties of a comparison adhesive layer, which, with otherwise identical features, in particular with regard to the materials used and the layer thickness, has not been stretched beforehand.
  • the chemical crosslinking in process step e) takes place using thermally induced and/or promoted chemical crosslinking, as can be achieved, for example, by adding a suitable chemical crosslinker.
  • this addition occurs in the PSA of the starting composite.
  • at least partial crosslinking of the PSA will occur before and during the stretching or subsequent relaxation.
  • the process is adjusted by the person skilled in the art, for example through the choice of the chemical crosslinker and/or its concentration, so that the PSA is sufficiently relaxed at the moment when the chemical crosslinking prevents further relaxation in order to achieve the desired isotropy of the macroscopic properties to enable.
  • a method according to the invention is preferred, with method steps d) and e) being carried out at least partially simultaneously.
  • method steps b), c) and d), preferably method steps b), c) and d) as well as e) are carried out simultaneously on different sections of a web-shaped material, and/or where the starting adhesive layer and the adhesive layer is present in the process as sections of a web-shaped material.
  • a method according to the invention is preferred, wherein the pressure-sensitive adhesive tape according to the invention is obtained after method step d) or e), preferably after method step e).
  • the invention also relates to a device for carrying out the method according to the invention, comprising a first guide arrangement with at least one guide roller for guiding a web-shaped initial composite and a second guide arrangement spaced from the first guide arrangement for guiding a web-shaped second carrier layer, the second guide arrangement comprising a driven rotation element .
  • Fig. 1 shows a schematic representation of the method according to the invention for producing a pressure-sensitive adhesive tape according to the invention in a preferred embodiment in side view.
  • the method according to the invention starts from a web-shaped starting composite 10, which in the example shown Fig. 1 was formed with a calender.
  • the initial composite 10 consists of a first carrier layer 12 and a third carrier layer 34, between which an initial adhesive layer 14 is arranged.
  • the first carrier layer 12 and the third carrier layer 34 are each web-shaped PET process liners, which have an average thickness of approximately 75 ⁇ m and are each coated with a silicone release layer in order to promote easier detachment of the PSA.
  • the starting adhesive layer 14 comprises a chemically at least partially uncrosslinked pressure-sensitive adhesive, which in the present example is designed as a poly(meth)acrylate-based pressure-sensitive adhesive, which is designed as a syntactically foamed pressure-sensitive adhesive by adding expandable or expanded microballoons.
  • the PSA in the example includes the Fig. 1 a chemical crosslinker, the concentration of which is adjusted so that the chemically at least partially uncrosslinked PSA has a relaxation ability when removed which almost corresponds to the relaxation ability of the completely uncrosslinked PSA.
  • the initial composite 10 is guided in the web direction at the speed v 1 with the aid of a first guide arrangement 16, with the first carrier layer 12 and the third carrier layer 34 each being guided over the driven guide rollers 26a, 26b of the first guide arrangement 16.
  • the PSA is transferred to a faster-moving second carrier layer 18 in order to obtain a web-shaped adhesive composite 20.
  • the pressure-sensitive adhesive is pulled off essentially tangentially from the first carrier layer 12 in the area of the guide rollers 26a, 26b. Due to the difference in speed, the pressure-sensitive adhesive is stretched.
  • the second carrier layer 18 is also designed as a PET process liner with an average thickness of approximately 50 ⁇ m.
  • the second carrier layer 18 is guided by the second guide arrangement 22 in the web direction at the speed v 2 , a driven roller being used as the rotation element 30, over which the second carrier layer 18 runs.
  • the average thickness is reduced, so that the thickness of the adhesive layer 24 (D 2 ) in the adhesive composite 20 in the example shown is reduced to approximately 25% of the thickness of the starting adhesive layer 14 in the starting composite (D 1 ), which in the present case is achieved by a Speed ratio v 2 /v 1 of approximately 4 is achieved.
  • the comparatively small stretching gap results in a stretching length of the PSA between the guide rollers 26a, 26b, which corresponds approximately to four times the radius r of the relatively compact rotating element 30 of the second guide arrangement 22. This can avoid an undesirable “neck-in”.
  • the relaxation step takes place in order to compensate for the reduction or anisotropy of the PSA caused by the stretching and the tension generated by the stretching.
  • the relaxation of the PSA in the adhesive composite 20 is supported after stretching by a heating element 32, which is designed as a radiant heater, whereby the Relaxation of the stretched PSA in the example shown takes place in such a way that the initial PSA of the unstretched PSA of the starting adhesive layer is largely restored and essentially isotropic macroscopic properties are obtained.
  • the method according to the invention can be operated particularly easily as a continuous or semi-continuous method, and for the purpose of further reducing the thickness, several of the drafting systems shown in the figures can also be arranged one behind the other, for example by using a drafting system according to Fig. 2 according to a drafting system Fig. 1 is downstream, so that the adhesive composite 20 of the first drafting system acts as an initial composite 10 in the next drafting system.
  • Fig. 2 shows a further schematic representation of the method according to the invention in a further embodiment.
  • the first guide arrangement 16 comprises only one guide roller 26a, which means that the third carrier layer 34 can be dispensed with as a further process liner.
  • the first carrier layer 12 is designed as a circumferential webbing, which is coated with a silicone release layer and on which the initial adhesive layer 14 can be applied, for example, using a conventional coating device.
  • FIG. 3 shows a schematic representation of the method according to the invention in a further embodiment.
  • the first guide arrangement 16 only has a guide roller 26a, but instead of the second guide roller 26b there is a release edge 28 around which the PET process liner is guided as a first carrier layer 12 in the area where the PSA is removed.
  • FIG. 4 an embodiment of the method according to the invention, wherein a web-shaped, stretchable inner layer made of a plastic is embedded in the pressure-sensitive adhesive, which is shown as a dashed line and which is also stretched in the method according to the invention.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Adhesive Tapes (AREA)
EP23171943.6A 2022-05-06 2023-05-05 Procédé de fabrication de bandes minces adhésives sensibles à la pression Pending EP4273202A1 (fr)

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DE102022111384.1A DE102022111384A1 (de) 2022-05-06 2022-05-06 Verfahren zur Herstellung dünner Haftklebebänder

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19939075A1 (de) * 1999-08-18 2001-02-22 Beiersdorf Ag Selbstklebendes Abdeckband unter Verwendung eines bahnförmigen Trägers auf Papier- oder Vliesbasis und einer lösungsmittelfrei und mastikationsfrei hergestellten und beschichteten druckempfindlichen Selbstklebemasse auf Basis nicht thermoplastischer Elastomere
EP1777276A1 (fr) * 2005-10-18 2007-04-25 tesa AG Procédé de préparation des masses auto-adhésives ayant des propriétés anisotropes
WO2015189323A1 (fr) 2014-06-11 2015-12-17 Tesa Se Polyester-polyuréthane

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161554A (en) 1958-11-05 1964-12-15 Johnson & Johnson Adhesive tape
US6004682A (en) 1991-09-09 1999-12-21 Avery Dennison Corporation In-mold label film and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19939075A1 (de) * 1999-08-18 2001-02-22 Beiersdorf Ag Selbstklebendes Abdeckband unter Verwendung eines bahnförmigen Trägers auf Papier- oder Vliesbasis und einer lösungsmittelfrei und mastikationsfrei hergestellten und beschichteten druckempfindlichen Selbstklebemasse auf Basis nicht thermoplastischer Elastomere
EP1777276A1 (fr) * 2005-10-18 2007-04-25 tesa AG Procédé de préparation des masses auto-adhésives ayant des propriétés anisotropes
WO2015189323A1 (fr) 2014-06-11 2015-12-17 Tesa Se Polyester-polyuréthane

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SATAS: "Handbook of Pressure Sensitive Adhesives Technology", 1999, pages: 153 - 203

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